True adherent when abruptly mishandled became unwell (5,3,7)

I believe the answer is:

under the weather

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'unwell' is the definition.
(thesaurus)

I cannot understand how the rest of the clue works.

(Other definitions for under the weather that I've seen before include "Sick" , "with clouds gathering overhead" , "Depressed" , "Seedy" , "put umbrellas up here?" .)

I've seen this clue in The Irish Times.

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